delphi

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre
« Reply #20 on: February 09, 2011, 09:10:57 PM »
Excellent news and exactly what I am looking for - you can count me in as an adopter as soon as its all available. The remaining issue for me is the choice and type of output stage - would you recommend the 1646? As my objective is transparency I am not looking to use transformers anywhere in the path.
All generalizations are false


promixe

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre New
« Reply #21 on: February 10, 2011, 08:39:32 AM »
Design Note 140 has quite a bit of info regarding 1570's output stages. I was contemplating using 1606 instead of 1646 (as it has differential inputs) but was suggested to use David Birt's output stage (Fig. 11 in DN140) instead. 1606/1646 could have up to 12dB higher noise than what 1570 is capable of. Therefore in the preamp channel PCB I'm gonna offer for sale (starting the design now) I'm gonna use something along the lines of LME49720 / LME49860 or alike performance wise.
« Last Edit: January 01, 2013, 08:45:21 PM by promixe »

delphi

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre
« Reply #22 on: February 11, 2011, 02:03:04 AM »
OK - thank you for the feedback - you are always one step ahead of me  :)

Just had a poke around looking at other suitable chips from Analog Devices but nothing jumps out that appears better than the National IC's you mention. Low noise and transparency are my two goals. Was interested to see the venerable 5532 was trotted out in the THAT Design Note! Its stood the test of time!

I will be very interested once you have finalized this design. Apart from the Five Fish SC3 preamp and the Seven Circle T15 (the former using THAT 1510 and the latter 1512 as the input gain stage, I have been surprised there haven't been more DIY projects centered on THAT chips as apart from some peoples misgivings about power rail voltage limits limiting its potential headroom - the specs seem to hold their own really well although I do realize that specs are just a small part of the puzzle in the real world.

How well do the National Chips handle long cable runs with consequent high capacitance??

Thanks
All generalizations are false

12volts

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre
« Reply #23 on: March 01, 2011, 06:00:10 PM »
Hi Delphi,

A couple of updates:

- Yes, I've ordered a new version of the adapter PCBs and should be receiving them by the end of February. The new version is optimized for performance a bit more and has some additional features I've been requested to add. More on that later, when I receive the boards.

- I also designed a PGA2500 DIP-28 adapter and it's being manufactured right now as well. The adapter has the same exact pinout as the chip itself, but it's quite more than just a SSOP-DIP generic adapter you can get elsewhere. It is made with audio performance in mind and features bypass caps as close as possible to power pins and a split digital/analog ground with an option to stitch them together (which I prefer, and which PGA2500EVM doesn't have).

- Both adapters will be available for pre-orders on my website, which I'm currently building for that purpose. I'm thinking hopefully  in a week or so, I'll launch the shopping cart and will post here, so people can start ordering.

.........et al


I have been using adaptor boards from Futurelec. SSOP - DIL, they too have PSU decoupling. They are 1.6mm FR6 material, DSPTH + silk screen, £0.42, €0.56 or $0.65 each for 25 off quantities.
They are particularly useful for for PGA XXXX designs. Why re-invent the wheel?   http://www.futurlec.com/SMD_Adapters.shtml
« Last Edit: March 01, 2011, 06:12:22 PM by 12volts »

promixe

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre New
« Reply #24 on: March 01, 2011, 06:51:31 PM »
Why re-invent the wheel?   http://www.futurlec.com/SMD_Adapters.shtml

I may be wrong, but taking a quick look at this adapter (which SparkFun also carries their version of here in the US) I see that it doesn't have a ground plane on the bottom. I find it somewhat of a problem for high-performance application since the return current has to now form a larger loop outside of the adapter, where it is more likely to cross-couple analog and digital sections. Also, traces for both inputs and outputs follow through vias, which pay small contribution to parasitic inductance. Again, it might not be so much of a problem at low frequencies, but I decided to create a PGA2500-optimized adapter with high-frequency routing disciplines in mind. It might be useful when interfacing ADCs. =) Beside having solid ground place underneath with an option to stitch together digital and analog sections, my adapter also has 2oz. of copper to reduce trace inductance (good for audio) and gold pads (probably has no effect on the end-user, but easier to work with on my end).

Afterall, the main purpose of the adapter is to ship it fully assembled (IR-soldered) to users who don't wish to deal with SMD. It may not be audibly superior (I'm yet to find that out) to a generic SSOP-DIP adapter, but I am certain there will be some subtle difference in measurements.



PS: The adapters will arrive this week, so, starting next week I can start taking orders from all who are interested. Thanks! =)
« Last Edit: January 01, 2013, 09:12:46 PM by promixe »

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre
« Reply #25 on: March 04, 2011, 03:18:39 PM »
great project! count me in for quite a few! maybe you know rme's micstasy, a state of art reference mic pre, has its price, it's popular especially among classical producers. Based on the pga2500 its remote concept -including auto set gain- is very cool, too. Perhaps theres something to 'copy'...
Ps is it possible to implement an overload detection which afaics the that doesn't have natively? and it seems that the that chip doesnt need any sort of pad, which is good in terms of noise.

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre
« Reply #26 on: March 04, 2011, 03:24:04 PM »
very interested, very broke.  i'll see what i can scare up when the time comes.
There's nothing like the right tool for the job.
And -usually- that's what I end up using...
..nothing like the right tool for the job!

promixe

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre New
« Reply #27 on: March 04, 2011, 04:17:46 PM »
Yes, RME Micstasy, Prism Sound Orpheus, Apogee Ensemble/Duet, Lavry Black and more high-end products all use PGA2500s in them. I recently had a chance to gut an Apogee Ensemble and found it to have a "datasheet-like" implementation of PGA2500 with Panasonic FC AC-coupling caps (not an "audiophile" choice =) followed by a fairly noisy output stage. And the preamps still sound really good! =) So, you can only imagine what you can do with the chip if you're not driven by mass-manufacturing constraints and do care about your own creation enough to not cheap out on it. =)

As far as THAT's overload detection, I will leave it up to the end-user to fiddle around with for now. If I see that this project generates steady interest in the next 2 months I will try to develop a Ethernet/MIDI remote control for it as well as the overload part. For now it's going to be front panel only control, but a very flexible and configurable one. I'll try to compile a manual for the controller by the end of next week, so people can get an idea of what it's going to be like.



The redesigned front panel board is now 100mm wide and 37mm tall, considerably smaller than the previous version. I got rid of the shift registers and am using just the uC now, saving end-user (minimal) costs, complexity and board space. To eliminate level-shifting logic between the uC and THAT5171 I decided to run the board at 3.3V, possibly limiting LED colors one can choose from (think blue Vf...). I'm yet to order prototypes and test them with all possible LED/color/button combinations... =)
« Last Edit: January 01, 2013, 09:11:54 PM by promixe »

tictac

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre
« Reply #28 on: March 10, 2011, 09:23:33 PM »
Any news about the 1570/1571 adapters?   

Do you have a link we can go to for purchase?

Thanks,

TT

promixe

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre New
« Reply #29 on: March 10, 2011, 09:47:55 PM »
Hi!
I'm in the process of assembling the first batch of adapters. I'll have 8 THAT adapters and 4 PGA adapters ready for shipping starting this weekend, but am open for orders up to 20 THAT adapters and any quantity PGAs. Mouser says lead time for the 1570 is 15 weeks. =( If there is a steady demand I'll order another batch of the 1570s from Profusion as they seem to be the only ones to carry them at the moment.

I don't have enough time to finish up my website for this weekend to buy stuff through it, but you can pay by paypal - PM me before paying. Each THAT or PGA adapter is $40. If you buy 8 or more of either or in combination they will be $35 each. Shipping is $5.80 within US. For international shipping please write me a PM with your shipping address and quantity of adapters you need - I'll give you total price.

I apologize for this temporary inconvenience of not being able to purchase these adapters through my website. I am working hard to finish it up ASAP.

Another update: I've been putting many many hours into the controller for these adapters and front panel PCB for it and it's going to be available for purchase by the end of March after my initial beta testing. I'm also working on cool channel PCBs for both THAT and PGA adapters. This would enable anyone to implement many channels of these fine digital pres very quickly. There are going to be many cool features in the preamps and the controller that I will reveal a bit later. A universal PSU for the project is coming also, as well as a metering PCB. I'm running out of free time right now a bit so it will be hopefully sometime in April that people will be able to buy all these cool things to build their own pres. I'll design and document a reference 8-channel preamp as well, so it's easier for people to build their versions of these things. Furthermore, if I see that people are interested in this project I am going to design a MIDI/Ethernet remote control extension for it... But let's see what happens in the next month or two first. =)

Thanks!
« Last Edit: January 01, 2013, 08:57:07 PM by promixe »


tictac

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre
« Reply #30 on: March 12, 2011, 11:46:52 AM »
So if I want to build a two channel mic preamp I would need two THAT1570/1571 adapters and one PGA adapter; is that correct?

Sorry for being such a Newbie but could you please explain what each of your boards do and how they will interface?

Thanks,

TT

promixe

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre New
« Reply #31 on: March 12, 2011, 05:39:40 PM »
So if I want to build a two channel mic preamp I would need two THAT1570/1571 adapters and one PGA adapter; is that correct?

If you want to build two channels of THAT1570/5171 mic preamp - then you need two THATDIP adapters. If you want to build two PGA2500 preamp channels you need two PGADIP adapters. They are two different kinds of preamps, although both digitally controlled.

For two channels of THAT you'd need two THATDIP adapters + one front panel controller to talk to them (unless you make your own, which, while not enormously hard to do, is not entirely trivial either =)  :



Later you can expand channels by adding more THAT adapters (up to 8 channels total) while keeping a single front panel controller to operate them all. I hope this makes sense.

Look at page 9 of THIS document to get an idea on how to design with THAT.
Look at page 4-2 of THIS document to see how PGA2500 could be implemented.

Beware that this is NOT a plug-n-play solution at the moment. You need to design the rest of the preamp to plug my adapters into. If you are not sure on how to do this it's better to wait another month or so for a reference design I'm working on right now. Then you would be able to buy a PCB from me, put the adapter into it and have a working high-performance preamp channel! The front panel controller I mentioned above is coming hopefully by the end of the month. I'm beta-testing it right now + putting finishing touches + writing an operation manual - a lot of work actually... =)
« Last Edit: January 01, 2013, 09:10:44 PM by promixe »

tictac

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre
« Reply #32 on: March 12, 2011, 10:25:44 PM »
Great, thanks for the clarification. I was thinking the PGA board was the front panel controller you mentioned. So it's really another preamp chip.

Sounds like the ticket for me is to wait your new reference pcb and front-end controller...

TT

promixe

Re: THAT1570/5171 DIP Adapter - Digitally Controlled Mic Pre New
« Reply #33 on: July 16, 2011, 11:27:33 AM »
wait your new reference pcb and front-end controller...

HERE IT IS! =)
« Last Edit: January 01, 2013, 08:51:12 PM by promixe »


 

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